To me, it looks like some one took a KS98 short version by Puma, carved out a place in the grip and placed an HJ diamond in it. The workmanship where the grip was cut out for the diamond is crap. The KS98 is (or was) good. Can not say if the HJ diamond is real or not. HJ not my thing (yet).
Went over to the Hitler Youth Militaria Collector forum to check on an HJ bayonet. There is a thread back in 2016 showing a KS98 long version with an HJ diamond placed in the grip like yours. The cut out for the HJ diamond was done very good on that one, but it is still BS. They say there is no such thing as an HJ bayonet. Would be a fantasy piece. Those guys there are the way about HJ stuff that the guys here are about K98s.
As a side thought, all of the " Hitler Youth bayonets" that are pictured, including yours, have different maker marks. That seems odd these "rare" (4 or 5) bayonets that I know of, all are made by different makers. I know HJ knives have a multitude (over 100) of makers and as such, if these HJ bayos were real and produced by more than one maker , you would think there would be more of them